The fact that Sunday’s bombing has immediately been blamed on “al-Shabab sympathisers” is hardly surprising, given events in Somalia in recent days.

The hand-grenade, thrown into a crowded public place, is becoming a grimly familiar tactic in Kenya. In the past six months, it has been used in bars in Mombasa, churches in Garissa near the Somali border, as well as churches and a bus station in Nairobi.

All of these attacks have initially been blamed on al-Shabab. But in at least some cases, subsequent reporting has suggested turf-wars between local gangs.

As Kenyan troops push al-Shabab out of its last Somali urban stronghold, Kismayo, there is nervousness about the possibility of a retaliation on Kenyan soil.

Many remember the bombings in Kampala in 2010, which killed 74 people, after Ugandan troops entered Somalia. Whatever the motive of Sunday’s bombing, it is not on a comparable scale.

A police spokesman, Charles Owino, told Reuters news agency: “We suspect this blast might have been carried out by sympathisers of al-Shabab.

“These are the kicks of a dying horse since, of late, Kenyan police have arrested several suspects in connection with grenades.”

The authorities said three children were seriously hurt in the attack, and a number of others suffered lighter injuries.

The Red Cross had earlier said six children were critically wounded.

Irene Wambui, who was in the church at the time of the attack, said: “We were just worshipping God in church when suddenly we heard an explosion and people started running for their lives.

“We came to realise that the explosion had injured some kids who were taken to hospital and unfortunately one succumbed.”